Method and system for femoral condylar resection arthroplasty of the knee

ABSTRACT

A method and system for femoral condylar resection arthroplasty (FCRA) of the knee, which preserves the undamaged meniscus, whether by arthroscopy or arthrotomy, and only replaces the damaged area of the femoral condyle. In one embodiment, both the distal and posterior femoral condyle are replaced with a two piece femoral two-piece distal and posterior femoral condyle component. This two piece component has a metal piece and a plastic piece removably attached in a tongue and groove arrangement. This arrangement allows the plastic piece to be removed when converting the FCRA into a unicompartmental arthroplasty.

This application is a continuation in part of U.S. patent applicationSer. No. 15/595,053 filed May 15, 2017, now U.S. Pat. No. 10,918,396issued Feb. 16, 2021, which is a continuation in part of U.S. patentapplication Ser. No. 15/464,241 filed Mar. 20, 2017, now U.S. Pat. No.10,918,399 issued Feb. 16, 2021, which is a continuation in part of U.S.patent application Ser. No. 15/427,016 filed Feb. 7, 2019, now U.S. Pat.No. 10,426,504 issued Oct. 1, 2019.

TECHNICAL FIELD

The exemplary teachings herein pertain to methods, systems, componentsand/or devices for femoral condylar resection arthoplasty (FCRA) of theknee.

BACKGROUND

Since Sir John Charnley pioneered the design and implementation of thetotal hip arthroplasty in the mid-1960s, joint replacement surgeons andorthopedic product companies have been striving to improve on theoriginal design, often in collaboration. These improvements have beenfocused on the following goals:

i) Improvement of patient function

ii) Ease of insertion, through improved instrument design and surgicalapproach

iii) Reproduction of beneficial results, both from the patient andsurgeon standpoints

iv) Longevity of the product

v) Smaller incisions

vi) Faster recovery

vii) Shorter operating time

viii) Multi-modal pain control parameters

Over the last fifty years, significant strides have been made in all ofthese goals. Newer products with improved materials have increasedcomponent longevity. Minimally invasive techniques, with multi-modalpain control, standardization of physical therapy protocols, andimproved instrument design have all improved patient function andshortened recovery time. Procedures being performed more frequently bysurgeons better versed in joint replacement surgery have led to morebeneficially reproducible results.

One of the primary goals of all joint replacement arthroplastytechniques and designs is to remove as little bone as possible toaccomplish the above goals. Always in the back of every jointreplacement surgeon's mind is the fact that if the patient lives longenough, of if they put undue stress across the joint, whether due tobeing too active, weight gain, or other factors, the prosthesis willfail. The smaller amount of bone removed at the time of the primaryarthroplasty, the less invasive revision necessary.

Unicompartmental arthroplasty of the knee has been part of the jointreplacement surgeon's armamentarium for over 35 years. Commonly, onlyone of the three compartments in the knee has damage and is symptomatic.The other two are normal. The unicompartmental arthroplasty allows forthe removal of the damaged compartment but preserves the patient'snormal and native undamaged compartments.

The standard design of the traditional unicompartmental kneearthroplasty (when replacing the medial or lateral compartments) is toreplace the distal and posterior condyles of the femur and the articularsurface of the tibial plateau of the involved compartment. The meniscusis removed.

Often there is damage to the distal femoral weight bearing surface, yetthe posterior femoral condyle and the tibial plateau articular surfacesare unaffected.

The following prior art references relate to and/or discuss one or moreof the above described issues, and are each herein fully incorporated byreference: U.S. Patent Application Publication Nos. 2007/0032876 A1entitled Knee Joint Prosthesis, published on Feb. 8, 2007, and200810132895 A1 entitled Instruments and Method for ArthroscopicArthroplasty of the Knee, published on Jun. 5, 2008, both by inventorRon Clark of Valparasio, Ind.

SUMMARY

One or more methods, systems, designs, instruments, implements,components and/or devices for femoral condylar resection arthroplasty(FCRA) of the knee are disclosed. In a preferred embodiment, only thedamaged femoral condyle of the knee (medial or lateral; distal and/orposterior, depending on the extent of damage) is replaced. By doing so,the method and system maintains the meniscus and corresponding tibialplateau, while replacing only the damaged surface of the femoral condyleand preserves normal tissue of the meniscus and tibial hyalinecartilage. This would be very beneficial in younger and more activepatients. The method and system does not preclude a “traditional”uni-compartmental arthroplasty at some point in the future should thatbecome necessary. The method and system can be performed with limitedexposure, post arthroscopy for correction of other intra-articular kneepathology. The surgical time and recovery would be shorter because ofthe less invasive nature of the procedure.

The one or more methods, systems, designs, instruments, implements,components and/or devices incorporate the following characteristicsand/or features:

1) Preserves the undamaged part of the meniscus. All currentunicompartmental arthroplasty techniques sacrifice the meniscus. In theprocedures disclosed herein, only the torn part of the meniscus isremoved in the first part of the process (surgical procedure) via thearthroscope.

2) Only replaces the damaged area of the femoral condyle (distal femoralcondyle or both distal and posterior femoral condyle). Whether toreplace the distal and/or the posterior femoral condyle is anticipatedthrough careful review of the pre-op MRI, but confirmed at arthroscopy.If there is significant damage to the tibial plateau as seen atarthroscopy, in the pre-operative MRI, or at the time of arthrotomy,then a traditional unicompartmental arthroplasty is performed.

3) While either plastic or metal material for the components may beused, preferably plastic components are used, as plastic articulating onthe hyaline cartilage tibial plateau will mimic nature better thanmetal.

4) Once the arthroscopic procedure is finished, the surgeon will thanmake a small (2-3 inch) incision, use the box retractor, slide in theintra-compartmental (IC) insert, place on the femoral cutting jig, fixit with pins, make the appropriate distal femoral cut, and cement in thecomponent. If the posterior is to be replaced, a chamfer and posteriorcut will be made, using existing cutting blocks.

5) The disclosed procedures may be performed by arthroscopic surgeons,in addition to joint arthroplasty surgeons.

The presently disclosure methods, systems, designs and instruments forfemoral condylar resection arthroplasty provide the joint replacementsurgeon and/or arthroscopic surgeon two primary options when performingfemoral condylar replacement of either the medial or lateralcompartments of the knee: 1) Replacement of the distal femoral condyleonly, when the posterior femoral condyle and the tibial articularsurfaces are both normal. This also allows for the preservation ofstable medial meniscal tissue; or 2) Replacement of the entire femoralcondyle, both distal and posterior.

Additional advantages and novel features will be set forth in part inthe description which follows, and in part will become apparent to thoseskilled in the art upon examination of the following and theaccompanying drawings or may be learned by production and/or operationof the teachings herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing figures depict one or more implementations in accordancewith the present teachings, by way of example only, not by way oflimitation. In the drawing figures, like reference numerals refer to thesame or similar elements.

FIG. 1 is a flow chart illustrating the procedure(s) according to thepresent disclosure.

FIG. 2A is a schematic diagram of a box retractor used in the method(s)and system(s) of present disclosure.

FIG. 2B is a schematic diagram illustrating an anterior view of the boxretractor of FIG. 2A.

FIG. 2C is a schematic diagram illustrating the tendon slots of the boxretractor of FIG. 2A.

FIG. 3A is a schematic diagram depicting a side view of anintercompartmental (IC) insert used in the method(s) and system(s) ofpresent disclosure.

FIG. 3B is a schematic diagram depicting a top view of theintercompartmental (IC) insert of FIG. 3A.

FIG. 4A is a schematic diagram depicting a front view of a cutting blockused in the method(s) and system(s) of present disclosure.

FIG. 4B is a schematic diagram depicting a side view of the cuttingblock of FIG. 4A.

FIG. 4C is a schematic diagram depicting a front view of an alternatecutting block used in the method(s) and system(s) of present disclosure.

FIG. 4D is a schematic diagram depicting a side view of the alternatecutting block of FIG. 4C.

FIGS. 5A-5D are schematic diagrams of trial components used in themethod(s) and system(s) of present disclosure, with FIG. 5A depicting afront view of a guide, FIG. 5B depicting a side view of a guide, FIG. 5Cdepicting a handle, and FIG. 5D depicting a distal femoral condyletrial.

FIG. 6 is a schematic diagram of a distal and posterior femoral condyletrial.

FIG. 7A is a schematic diagram depicting a side view of a combined,one-piece Intra-condylar insert and distal femoral cutting block.

FIG. 7B is a schematic diagram depicting a front view of a combined,one-piece Intra-condylar insert and distal femoral cutting block.

FIG. 8 is a schematic diagram depicting a two-piece implant distalfemoral condyle, illustrating the two pieces prior to attachment.

FIG. 9 is a schematic diagram depicting a two-piece implant distalfemoral condyle, illustrating the two pieces attached together.

FIG. 10 is a schematic diagram depicting a two-piece implant distalfemoral condyle, illustrating the two pieces after being separated ordetached.

FIG. 11 is a schematic diagram illustrating the two-piece distal femoralcondyle replacement implanted into the knee.

FIG. 12 a schematic diagram illustrating a side view of the knee withthe cutting block pinned in place.

DETAILED DESCRIPTION

The following description refers to numerous specific details which areset forth by way of examples to provide a thorough understanding of therelevant method(s) and system(s) disclosed herein. It should be apparentto those skilled in the art that the present disclosure may be practicedwithout such details. In other instances, well known methods,procedures, components, instruments, implements and/or devices have beendescribed at a relatively high-level, without detail, in order to avoidunnecessarily obscuring aspects of the present disclosure.

FIG. 1 is flow chart illustrating the method(s) for the presentdisclosure for femoral condylar resection arthroplasty of the knee, withreference to the component(s) used during the method(s). Prior to adecision to proceed with distal or complete femoral condylararthroplasty (FIG. 1 , Step 3), an evaluation of a patient's knee mustbe undertaken (FIG. 1 , Step 1A and/or Step 2), or a referral from anArthroscopist is made (FIG. 1 , Step 1B). Once the decision to proceedis made, the method includes the following steps: Step 4—anapproximately two inch incision is made over joint line. As is wellunderstood by one of ordinary skill in the art, the joint line of theknee refers to the anatomic interval between the distal femoral condyleand the proximal tibial plateau. These two anatomic areas comprise theknee joint. The box retractor of FIGS. 2A-2C is used. Step 5—theintercondylar insert of FIGS. 3A-3B is placed between articular surfacesof distal femoral condyle and tibial plateau with knee in extension.Step 6—the distal femoral condyle cutting block of FIGS. 4A-4B is pinnedat “tide mark.” Step 7—the distal femoral condyle resected. Step 8A—ifthe distal femoral condyle only to be replaced, perform Step 9: sizetrial, drill peg holes and cement using the trial components of FIGS.5A-5D. Step 8B—if distal and posterior condyles to be replaced, performStep 10: use traditional posterior and chamfer cutting block, makeappropriate cuts, size trial, drill peg holes and cement using the trialcomponents of FIGS. 5A-5C and 6 .

FIGS. 3A and 3B illustrate the intra-compartmental insert (IC Insert).This insert has a curvilinear, pliable plastic surface that will be usedfor FCRA procedure. The joint replacement surgeon will use his or herpreferred system for a traditional unicompartmental replacement. It is1.5 cm wide. The curvilinear plastic component will be placed in betweenthe tibial and femoral articular surfaces. The handle of the IC Insertwill be hard plastic or metal and will contain a hole for placement ofthe external alignment guide.

FIGS. 4A-4B illustrate the distal femoral cutting block. This block willbe attached to the IC Insert. Preferably, there will be neutral cuttingslot. By slight angulation of the cutting block, e.g., 1 degree, 2degree, or 3 degree superior slope, more or less of the distal condylecan be removed. This will allow a slight increased coverage if thedistal femoral condyle wear extends slightly into the posterior condyle.However, unless otherwise determined, a neutral cut should be made. Analternate distal femoral cutting block is disclosed in FIGS. 4C-4D, andincludes one or more guidewire slot(s) (two shown) through which one ormore guidewire(s) can be placed to help line up the bone cut, asdiscussed in more detail below.

FIGS. 2A-2C illustrate the box retractor. This box retractor is aretractor designed specifically for the FCRA procedure. Since theincision only needs to expose the most inferior aspect of the distalfemur and most superior aspect of the tibia, it may be relatively small.However, the patella, the patellar and quadriceps tendon, and theopposite capsular structures must be retracted to allow placement of theinstruments and allow visualization of the bone cuts, trial sizing, andthen placement of the definitive component. There are four right angleblades (two for medial structures and two for lateral structures), whichmay be either metal or hard plastic (if necessary to place the retractorunder the patella itself). The blades come in two depths, shallow anddeep. The metal lattice support is movable superior/inferior andmedial/lateral to allow for adequate exposure. This also keeps theretractor in place while flexing and extending the knee.

FIG. 5D illustrates the distal femoral condyle replacement component ortrial. There are three possibilities for the distal femoral condylereplacement:

1) Metal component with at least two pegs cemented into the distalfemoral condyle;

2) Plastic component with at least two pegs cemented into the distalfemoral condyle; and

3) Metal back component with at least two pegs cemented into the distalfemoral condyle, with snap on plastic liners of various thicknesses.

Whether the distal femoral condyle is replaced, or both the distal andposterior femoral condyles are replaced, the trial components are madeof plastic.

If the implanted metal component is used, this is a single component. Ifthe implanted polyethylene is used, this is a single component.

However, if the metal backed component (cemented into bone) is used withthe polyethylene component that will articulate with the tibial plateauhyaline cartilage and the remaining meniscus, this is a two piecefemoral condyle implanted component as illustrated in FIG. 8 . This twopiece component is used only when both the distal and posterior femoralcondyle is replaced, not when the distal femoral condyle only is beingreplaced.

In the embodiment illustrated in FIG. 8 , the surface of the metalcomponent in the two-piece implant includes structural features,preferably but not limited to grooves, for attachment of thepolyethylene surface. The surface that the polyethylene will affix to,can be polished and be made of same metal as the current femoralcondylar components of traditional unicompartmental systems (e.g.chromium cobalt, oxinium, titanium). However, the metal component willpossess grooves that will allow the polyethylene surface to be affixedto it in a tongue and groove type fashion, as illustrated in FIG. 9 .

At the time a revision from the FCRA to a traditional unicompartmentarthroplasty may become necessary, a small osteotome or freer tool canbe used to remove or separate the original polyethylene component fromthe metal component, as shown in FIG. 10 . This will then allow theremaining metal component from the original FCRA to be used, obviatingthe need to replace the femoral component. Only the tibial articularsurface will need to be replaced.

The plastic component is preferably formed as one solid piece, andincludes structural features, preferably but not limited to ridges, forattachment of the metal surface. This piece, by way of thetongue-in-groove arrangement, will snap-fit into the metal component,i.e., the ridges into the grooves. The polished metal surface will becemented into the bone, after the trial determines the proper size. Thepolyethylene component will then be snapped fitted into the metalcomponent, (FIGS. 8 and 9 ). If/when the FCRA then needs to convertedinto a unicompartmental arthroplasty, advantageously, only thepolyethylene component is removed. It is unsnapped from the cementedmetal component (FIG. 10 ). Advantageously, the surgeon does not have toremove the metal component from the bone, which to do so would entailremoving more bone. Thus, femoral condyle bone is preserved. This alsowill decrease the surgical time, because the metal component will nothave to be removed. To convert to a unicompartmental arthroplasty, onlythe tibial metal component with its polyethylene component will have tobe put in. The femoral component is already in the place, i.e., thepolished metal component that was cemented as part of the original FCRA.

FIG. 11 is a schematic diagram illustrating the distal femoral condylereplacement component comprising the metal backed component used withthe polyethylene component and being cemented into the femur bone.

FIG. 12 a schematic diagram illustrating a side view of the knee jointprior to the distal femoral condyle replacement, and illustrating thecutting block pinned in place. Having the pins in both the distal femurand proximal tibia allows the surgeon to make the distal femoral condylecut either with the knee flexed or extended. If the surgeon choses tomake the bone cut in extension, having pins on both sides of the jointwill allow a more stable cut. Once the cut is made, either partially orfully, the tibial pins may be removed and the knee flexed to inspect thecut. However, the surgeon may choose to insert only the femoral pins,flex the knee, and then make the distal femoral condylar bone cut.

The various steps and components discussed with respect to FIG. 1 aredescribed in further detail below.

Pre-Operative Planning

As with any contemplated joint replacement, it is important that acomprehensive history pertaining to the patient's knee is obtained and adetailed physical exam of the knee is performed. Plain radiographs andan MRI need to be carefully evaluated. When considering a FCRA, thereare important parameters to consider. No single one is absolutelydefinitive. These all need to be considered and discussed with thepatient so he or she is involved in the decision making process (the artof medicine).

History

Where is the patient's pain located? If primarily around the involvedcompartment, an indication that FCRA may be indicated. If more diffuseand widespread, a FCRA may not be indicated.

When does it bother the patient? If primarily with weight bearing and/orgoing upstairs, more indicative of single compartment damage. Ifsignificantly present even without weight bearing, and when goingdownstairs, the damage may be more widespread and involve the patellaand trochlea surfaces.

Does the knee give out with twisting activities? More likely damage tothe weight bearing surface. Of course, there could be a localizedmeniscus tear without damage. Diagnostic testing will help determinethis.

Physical Examination

Is there a deformity with weight bearing; genu varus with damage to themedical compartment, genu valgus with damage to the lateral compartment?Is there observed instability with ambulation? If so, these are acontraindication to a FCRA.

Is the pain confined to one compartment with palpation? The presence ofpain to palpation to multiple compartments could indicate that there ismore than one compartment damaged.

Is there substantial loss of range of motion? A loss of more than fivedegrees of full extension or flexion less than 125 is a relativecontraindication for FCRA.

Is there ligamentous laxity? Mild apparent medial or lateral laxity isto be expected when a mild genu varus or genu valgus deformity ispresent. Substantial medial or lateral laxity, or anterior or posteriorlaxity, is contraindications to FCRA.

Are pain, crepitation, and mechanical findings confined to one weightbearing compartment with meniscal testing? If more than one compartmentis involved, this may indicate that the FCRA is not appropriate, orthere are bi-compartmental meniscus tears.

Plain Radiographs

A minimum of four views should be obtained: standing AP, standing PA,lateral, and the patellar trochlear view of the surgeon's choice (e.g.Houghston, sunrise, etc.).

The angle between the femur and tibia on the standing AP will need to bemeasured. While this can be measured on the computer screen of theelectronic views, it is recommended that hard copies be obtained on anypatient that FCRA is being considered. This will allow more accuratemeasurement be made to determine genu varus and genu valgus. A varusangle greater than five and a valgus angle greater than 8 is a relativecontraindication to FCRA, as it suggests that instability may bepresent. If the contralateral knee is normal, that knee should bemeasured and compared to the knee being considered for FCRA.

The amount of narrowing and subchondral sclerosis needs to be determinedon the standing radiographs. Both the standing AP and PA need to beevaluated to assure that only one of the weight bearing compartments isdamaged. Narrowing, the genu angle, subchondral cysts, and subchondralsclerosis are all important to consider.

There are two specific areas to consider on the lateral view. The firstis to determine if there are osteophytes at the superior and inferiorpole of the patella, and the superior trochlea. If substantial, theseosteophytes would indicate that there is patella trochlear damage andmay be a contraindication to FCRA. The second is to review the posteriorcondyle of the compartment being considered. The presence ofosteophytes, subchondral cysts, and subchondral sclerosis would indicatethat a traditional unicompartmental may be necessary.

The patella-trochlear view will need to be examined for two findings.The first is for substantial signs of degeneration: osteophytes,narrowing, subchondral cysts, and subchondral sclerosis. If substantial,the patient may require a total knee replacement. The second is forlateral patella tilt or subluxation. If the unicompartmentalarthroplasty being considered is medial, and if a genu varus deformityis overcorrected, this may lead to increased patella trochlearinstability and degeneration, causing rapid failure and necessitatingrevision to a total knee.

After careful consideration of the patient's history, physicalexamination, and review of plain radiographs, a determination should bemade if the patient is a possible candidate for FCRA. If the patient isdetermined to be a candidate, than an MRI should be obtained. (FIG. 1 ,Step 1A) There are six areas that specifically need to be scrutinized:

The patella and trochlea: The integrity of the subchondral bone andhyaline cartilage of each need to be determined. Substantial damage toeither or both, especially when correlated with findings on the historyand physical, would indicate a total knee or bicompartmentalarthroplasty is indicated.

The opposite compartment: The integrity of the subchondral bone, thehyaline cartilage, and the meniscus need to be determined. If there isno significant damage to the compartment, yet the meniscus is torn, anarthroscopic meniscectomy on the opposite compartment will need to beperformed at the same time as the FCRA.

The distal femoral condyle and underlying hyaline cartilage: Damageneeds to be determined and confirmed.

The posterior femoral condyle and underlying hyaline cartilage: If notdamaged, the distal femoral FCRA may be indicated. If substantialdamage, than both the distal and posterior condyle will needreplacement.

The meniscus of the involved compartment: If torn, than eitherarthroscopic or open partial meniscectomy will need to be performed atthe time of the FCRA. (FIG. 1 , Step 2).

Tibial plateau and overlying hyaline cartilage: If normal, than a FCRAcould be indicated, after considering the history, the physicalexamination, review of the plain radiographs, and MRI.

Instrumentation

Intra-compartmental Insert (IC Insert): This has a curvilinear, pliableplastic surface that will be used for the FCRA procedure. The pliableplastic surface will not cause any damage to tibial articular surface,as opposed to a metal insert. It is 1.5 cm wide. The curvilinear plasticcomponent will be placed in between the tibial and femoral articularsurfaces, over the anterior meniscus. The handle of the IC Insert willbe hard plastic or metal and will contain a hole for placement of theexternal alignment guide, if the surgeon's preference is such. (FIGS.3A-3B).

External Alignment guide: If used, this will be inserted through thehandle of the IC insert to check for AP and lateral alignment prior tofixation of the distal femoral cutting block to the proximal tibia, ifthe surgeon feels it is necessary to check this.

Distal femoral cutting block: This block will be attached to the ICInsert. Preferably, there will be neutral cutting slot. By slightangulation of the cutting block, e.g., 1 degree, 2 degree, or 3 degreesuperior slope, more or less of the distal condyle can be removed. Thiswill allow a slight increased coverage if the distal femoral condylewear extends slightly into the posterior condyle. However, unlessotherwise determined, a neutral cut should be made. (FIGS. 4A-4B).

Alternate distal femoral cutting block: This block will be attached tothe IC Insert through the slot for the IC Handle. On each side of theblock at the level of the cutting slot is a slot, preferably a roundslot, for placement of a guidewire. This guidewire will be placedagainst the bone of the femoral condyle to be cut. The surgeon will usethis to assure the proper distal femoral cut. One of the uniquefunctions and advantages due to the flexibility imparted by the plasticmaterial of the IC Insert is that once the femoral cutting block isplace over the IC Insert handle, the surgeon is able to change theposition of the femoral cutting block once aligned with the guide wireplaced in its slot. This assures the correct distal femoral cut. Thedistal femoral cutting block is then pinned into place prior to makingthe distal femoral cut. (FIGS. 4C-4D).

FCRA (Box) retractor This is a retractor designed specifically for theFCRA procedure. Since the incision only needs to expose the mostinferior aspect of the distal femur and most superior aspect of thetibia, it may be relatively small. However, the patella, the patellarand quadriceps tendon, and the opposite capsular structures must beretracted to allow placement of the instruments and allow visualizationof the bone cuts, trial sizing, and then placement of the definitivecomponent. There are four right angle blades (two for medial structuresand two for lateral structures), which may be either metal or hardplastic (if necessary to place the retractor under the patella itself).The blades come in two depths, shallow and deep. The metal latticesupport is movable superior/inferior and medial/lateral to allow foradequate exposure. This also keeps the retractor in place while flexingand extending the knee while assessing the component. (FIG. 2A-2C).

Components

Finite Element Analysis defines the function of the knee to be one ofvarious contact points between structures of different mesh densities.(Pfeiffer, F. M., Volume 29, Number 2, 2106, The Journal of KneeSurgery.) The knee weight bearing areas consist of three structures ofdifferent densities, bone (rigid, the distal femur and proximal tibia),hyaline cartilage (semi-rigid, the femoral and tibial articularsurfaces) and the meniscus (soft, the medial and lateral meniscus).

Traditional Uni-compartment and total knee replacement has evolved sothat a rigid surface (the femoral component) articulates with asemi-rigid surface (the polyethylene) liner of the tibia and thepolyethylene patella component). This has worked well over the years andremains the mainstay of knee replacement arthroplasty.

However, observed during arthroscopic surgery on the knee, often timesthere exists a partial meniscus tear, which in turn has damagedsubstantially the corresponding gliding surface of the distal and/orposterior femoral hyaline cartilage, while leaving the tibial hyalinecartilage normal. Currently, arthroscopic debridement of the damagedfemoral articular surface and removal of the torn meniscus is all thatcan be offered from a mechanical standpoint to help these patients.Hyaluronidase injections, anti-inflammatory medications, knee supports,and orthotics can sometimes help these patients. Commonly, thecompartment involved in these patients quickly deteriorates to where aUni-compartment arthroplasty becomes necessary.

Since the tibial articular surface is essentially undamaged and much ofthe meniscus remains intact, the basic geometry of the compartment isnormal, except for the damage to the femoral gliding surface.Accordingly, the presently disclosed method(s) would not replace theentire compartment. The presently disclosed method(s) would just replacethe damaged distal femoral hyaline surface, while leaving the tibialarticular surface and undamaged meniscal tissue intact.

Since the hyaline cartilage surface is a semi-rigid surface, replacingit with a rigid surface (the current metal surfaces being used) would beexpected to cause progressive damage to the tibial hyaline surface. Itwould be more physiologically compatible to replace it with a less rigidsurface. That way, the semi-rigid against semi-rigid surface of thenormal hyaline cartilage would be preserved. The “plastic deformation”that occurs in the femoral articular surface at the junction of trochleaand the distal femoral condyle, is the so called “tide-mark.” These aresemi-rigid surfaces, not rigid surfaces.

Currently, with today's materials, the replacement of the distal femoralcondyle should be a polyethylene component. That way, two semi-rigidsurfaces would be articulating (i.e. polyethylene femoral condyle andnative tibial hyaline cartilage), rather than a semi-rigid surface(native tibial hyaline cartilage) against a rigid surface (metal distalfemoral component). However, laboratory testing can aid in thedetermination of the most appropriate surface for replacing the distalor distal/posterior femoral condylar surface.

There are three embodiments for the femoral condyle replacement, whetherthe distal femoral condyle or both the distal and posterior femoralcondyles. Preferably a polyethylene component with at least two pegs forcement fixation into the femur is used. A second, alternative componentwill be a metal back component with at least two pegs cemented into thefemur with snap on polyethylene liners of various thicknesses. The thirdembodiment is a metal component with at least two pegs cemented into thedistal femur.

FCRA Surgical Technique

An arthroscopic procedure may first be performed. If necessary, apartial meniscectomy will need to be performed. (FIG. 1 , step 2). It isunusual that there will be a significant amount of damage to the distalfemoral condyle to warrant a FCRA without meniscal tearing. Whetherperformed arthroscopically or as part of the open procedure, theremaining meniscus need to be well-balanced and stable, especiallyposteriorly. Steps 1A and 2 may previously have been performed by anArthroscopist who refers the patient for the FCRA. (FIG. 1 , Step 1B).

If an arthroscopy is performed first, arthroscopic portal on the sidehaving the open procedure may be vertical, and closer to the midlinethan what the surgeon is used to. This will allow the arthroscopicincision to be incorporated into the open procedure. Of course, thisdepends on where the surgeon normally makes his or her portal. However,if the surgeon prefers a horizontal incision, made slightly medially orlaterally to the midline, that is very acceptable.

After a decision to proceed with the FCRA is made (FIG. 1 , Step 3), asmall vertical arthrotomy incision (which would be approximately 2-3inches) is made slightly medially or laterally to the patellar tendon,depending on what compartment is involved. (FIG. 1 , step 4) The boxretractor is positioned (FIGS. 2A-2C). As with any surgical technique,the incision needs to be long enough to allow adequate visualization.Initially, it is recommended that the incision be made longer, and thenmay be shortened as the surgeon gains confidence in the procedure.

The “tide mark” is checked and marked with the knee in its fullextension. With the knee remaining in extension, a slight valgus stress(for medial compartment) or varus stress (for lateral compartment) isimparted and the pliable plastic portion of the IC insert (FIGS. 3A-3B)is then inserted over the anterior third of the meniscus in between thedistal femoral condyle and tibial plateau. (FIG. 1 , Step 5). Theanterior meniscus usually sits slightly inferior to the medial tibialarticular surface and is pliable enough to normally allow the IC Insertto be placed into the medial compartment without difficulty. In unusualcases where the IC Insert cannot be placed over the anterior meniscus,the anterior meniscus can be incised at this time and repaired at theend of the case.

The femoral cutting block (FIGS. 4A-4B) is attached to the IC Insert,making sure the cutting slot aligns with the tide mark, and is thenaffixed with two pins into the distal femur. (FIG. 1 , Step 6) Ifsurgeon preference, the external alignment guide is then insertedthrough the metal handle of the IC Insert and the AP, lateral, androtational planes are checked. It is important not to place the ICInsert against the tibial spine, as this will cause external rotation ofthe cutting blocks. However, since the tibial articular surface is notbeing resected, rotation of the implanted femoral component will bedetermined prior to cementing. The external alignment guide may not benecessary.

Once alignment and rotation is confirmed, the distal femoral cuttingblock is pinned to the tibia. This allows secure fixation. The distalfemoral is then cut. (FIG. 1 , Step 7) If the posterior condyle is alsoto be removed, the surgeon will use his or her standard system for theposterior and chamfer cuts. (FIG. 1 , Steps 8B and 10).

All the instrumentation is now removed. The trial components are trieduntil the proper size is determined. (FIGS. 5A-5C and 5D or 6 ). It isimportant that trial component is not proud either anterior orposterior, but rather are recessed. If proud anteriorly, this can causeimpingement on the patella. If proud posteriorly, this can causeimpingement on the posterior meniscus (if saved, or on the posteriortibial articular surface if not. The knee is put through a ROM to makesure there is not impingement anteriorly or posteriorly.

The fixation posts are then drilled after confirmation of proper size,motion, and setting of the trial is confirmed. (FIG. 1 , Step 9 or 10).The distal femoral component (FIG. 1 , Step 9; and FIG. 5D) or thedistal and posterior femoral condyle trial (FIG. 1 , Step 10; and FIG. 6) is then cemented into place. Excess cement is removed after the cementhardens. Again, a check is made to assure no impingement.

The knee is irrigated, tourniquet released if used, and hemostasisobtained. The surgeon will need to determine if a drain is necessary. Noimmobilization is required unless preferred by the surgeon.

This process is amendable to the use of computer generation of thecomponents. When the surgeon and patient have decided that this methodof treatment may be appropriate, the surgeon can submit the patient'sMRI results for computer analysis. A computer and software can evaluatethe MRI results to confirm whether or not the patient is a candidate forthe FCRA based upon an analysis of the data. The computer analysis willdetermine the need for a FCRA. First, by use of the MRI, a tear of themeniscus will be determined, if present or not. Secondly, the MRIcomputer analysis will determine if there is any damage to the tibialarticular surface. If there is, the patient is not a candidate for aFCRA. Thirdly, the MRI computer analysis will determine the extent ofthe femoral articular damage; the depth, the location and size. Ifsignificant damage is present, the computer can generate a design of acombined Intracondylar insert/distal femoral cutting block, and also adesign of an implantable component. If both distal and posterior femoralcondyles are to be replaced, the surgeon will use the MRI computergenerated combined Intracondylar insert/distal femoral cutting block forthe initial cut. The chamfer/posterior cuts would then be made.

Upon confirmation that the patient is a candidate for the FRCA, the onepiece, patient-specific design of a combination of the Intra-condylarinsert and distal femoral cutting block can be generated by the computerand software based on the patient's MRI data, appropriate for the size,shape and location relative to the patient's specific knee structure.This will be fabricated of a composite material that will not cause anydamage to the tibial articular hyaline cartilage surface. A trialcomponent can also be included with the patient specific cutting blockand implantable component.

This one piece Intracondylar insert/distal femoral cutting blockcomponent will then be use in the surgical procedure. FIG. 7Aillustrates a side view of the combined, one-piece Intra-condylar insertand distal femoral cutting block. FIG. 7B is a front view of thecombined, one-piece Intra-condylar insert and distal femoral cuttingblock.

Also included will be the definitive, patient specific component to beimplanted, the design of which is also generated by the computer andsoftware from the patient's MRI data, appropriate for the size, shapeand location relative to the patient's specific knee structure, whetherdistal femoral condyle or combination of distal and posterior femoralcondyle.

After the arthroscopic aspect of the procedure, at the time of the FCRAsurgery, the surgeon will place the patient-specific intra-condylarinsert between the distal femoral condyle and tibial articular surface,pin the attached cutting block in place, make the distal femoral cut(and posterior and chamfer cuts if the both distal and posteriorcondyles are to be replaced), check the trial component, and then cementin the implant included.

While the embodiment(s) disclosed herein are illustrative of thestructure, function and operation of the exemplary method(s), system(s),component(s) and device(s), it should be understood that variousmodifications may be made thereto with departing from the teachingsherein. Further, the components of the method(s), system(s),component(s) and device(s) disclosed herein can take any suitable form,including any suitable components capable of adequately performing theirrespective intended functions, as may be known in the art.

While the foregoing discussion presents the teachings in an exemplaryfashion with respect to the disclosed method(s), system(s), component(s)and device(s) for femoral condylar resection arthroplasty of the knee,it will be apparent to those skilled in the art that the presentdisclosure may apply to other arthroscopic and/or arthroplasty surgicalmethod(s) and system(s). Further, while the foregoing has described whatare considered to be the best mode and/or other examples, it isunderstood that various modifications may be made therein and that thesubject matter disclosed herein may be implemented in various forms andexamples, and that the method(s), system(s), component(s) and device(s)may be applied in numerous applications, only some of which have beendescribed herein.

What is claimed is:
 1. A method for a medial or lateral unicondylar femoral condylar resection arthroplasty of the knee, comprising the steps of: preserving undamaged meniscus in the knee via arthroscopy or arthrotomy; making an incision over a joint line of the knee; placing an intercondylar insert between articular surfaces of a distal femoral condyle and a tibial plateau with the knee in extension; pinning a distal femoral condyle cutting block at a tide mark; resecting the distal femoral condyle; using a posterior and chamfer cutting block; resecting the posterior femoral condyle; sizing the distal and posterior femoral condyle with trial components; and replacing the distal and posterior medial or lateral femoral condyle with a correspondingly sized two-piece distal and posterior femoral condyle component.
 2. The method of claim 1, wherein the two piece distal and posterior medial or lateral femoral condyle component comprises a polyethylene piece and a metal piece.
 3. The method of claim 2, wherein the step of replacing the distal and posterior medial or lateral femoral condyle with a correspondingly sized two-piece distal and posterior femoral condyle component further comprises attaching the metal piece and the polyethylene piece via tongues and grooves. 